An impossibility theorem for gerrymandering • Hacker News Board

Re: An impossibility theorem for gerrymandering

#11

Post by bloaf » Thu, Oct 12, 2017, 4:17 PM UTC

cousin_it wrote: post #9

dragontamer wrote: post #4

So the question is if "Minimizing Efficiency Gap" is what we should be aiming for. Its a solid proposal, but I guess its up to the courts to decide if "Efficiency Gap" is a good metric. I guess I'll be interested in hearing the arguments as they come up.

It seems to me that a system with zero efficiency gap would be equivalent to one big election with proportional representation. If that's what people really want, why talk about voting districts at all?

If I had to guess, I would say that there is at least some benefit to having politics be local. That is, it may be better to ask people to choose between a small number of "local" candidates, rather than a large cohort of state-wide candidates.

Re: An impossibility theorem for gerrymandering

#12

Post by rndmize » Thu, Oct 12, 2017, 4:24 PM UTC

> Now suppose you are tasked with drawing 5 districts for this region.

Or, we could go with proportional representation, make it a single district, and now we can reasonably expect to get 2-3 blue reps and 2-3 red ones, handling both the districting problem and efficiency/fairness problem in one go.

Re: An impossibility theorem for gerrymandering

#13

Post by tveita » Thu, Oct 12, 2017, 4:25 PM UTC

It's strange that there's so much focus on district shapes, when any voting system with proportional representation would make gerrymandering pretty much ineffective.

Every voting system has its flaws, but the US system seems to have particularly few advantages.

Re: An impossibility theorem for gerrymandering

#14

Post by waegawegawe » Thu, Oct 12, 2017, 4:27 PM UTC

tveita wrote: post #13

It's strange that there's so much focus on district shapes, when any voting system with proportional representation would make gerrymandering pretty much ineffective. Every voting system has its flaws, but the US system seems to have particularly few advantages.

It's not really "strange." The chances of us ever going to a proportional system en masse are near zero. The chances of making extreme gerrymandering illegal are significantly better (the Supreme Court recently heard a case about it).

Many people prefer to spend time thinking within the context of what is likely to happen. That's not to say we don't need folks who dream big, but we need more than just those folks.

Re: An impossibility theorem for gerrymandering

#15

Post by notfromhere » Thu, Oct 12, 2017, 4:29 PM UTC

tveita wrote: post #13

It's strange that there's so much focus on district shapes, when any voting system with proportional representation would make gerrymandering pretty much ineffective. Every voting system has its flaws, but the US system seems to have particularly few advantages.

stable oligarch control is pretty much the only advantage

Re: An impossibility theorem for gerrymandering

#16

Post by sova » Thu, Oct 12, 2017, 4:29 PM UTC

The Supreme Court (id est The Highest Court of the Land) is currently evaluating if they can rely on an algorithm to detect Constitutionality of district shapes. You're kidding, right? As a computational scientist this is concerning to put it mildly.

Trying to ensure proportionality in representation... is that the intended goal? Is this even a meaningful pursuit in a bicameral system? The Supreme Court makes rulings that span time infinitely forward, meaning that all those different parties that have existed since the inception of the Union have dissolved and new ones have been formed since, but the rulings of the Supreme Court have not this luxury of death and recycling. Nay, a ruling by the court is very potent and quite a footprint on the legal plain.

So there is no easy way to ensure that a district is Constitutionally Compliant, but we can definitely point out "unconstitutional districting" -- right? Do you agree?

Re: An impossibility theorem for gerrymandering

#17

Post by dragontamer » Thu, Oct 12, 2017, 4:31 PM UTC

Retric wrote: post #6

dragontamer wrote: post #5

Earlier quoted context omitted.

> why shouldn't it win every district? Because we are supposed to have a representative government. If there's 55% Blue voters and 45% Red Voters, you're supposed to ideally have 55% Blue representatives and 45% Red representatives. The example is a counterexample of this concept. Instead of 55% Blue / 45% Red split, the map as a whole becomes 100% blue. This is almost the very definition of "Tyranny of the Majority"…

If votes are 80-20 then it's not necessarily possible or reasonable to draw 80 vs 20 winning districts.

Which states are 80-20 in America?

Maryland is an example of a highly gerrymandered state (towards Democrats, although there are many Republican examples too). Maryland voted 60.5% Clinton / 35.3% Trump, which suggests that they have (roughly) 2 Democrats for every 1 Republican in the state.

However, due to the significant gerrymandering in Maryland, there is ONE Republican and SEVEN Democrats in the House. That's certainly not fair towards Republicans who live in Maryland.

EDIT: Apparently North Carolina is the Republican example to talk about, in case you want some "balance".

Re: An impossibility theorem for gerrymandering

#18

Post by simonh » Thu, Oct 12, 2017, 4:31 PM UTC

js2 wrote: post #3

I'm confused about the example. First of all, it seems highly unlikely such a distribution of red and blue votes would occur. But more importantly, blue is a majority of every 3x3 square - why shouldn't it win every district?

It seems to me that probably the outcome of an election should mainly be determined by the decisions of voters, not mainly by how the voting districts are drawn.

Imagine that a few voters in each district change their minds, some from each party switch to the other. Even if the overall effect is a very slight swing towards red you could still end up with all the districts going to red. Or with the same swing but distributed differently you could still end up with blue winning (though not by as much), even though it had fewer total votes.

So it's not about what should happen in any one particular snapshot. That's just a single example. It's about how well the outcome of a series of elections should reflect the wishes of voters as a whole. I'm not a big fan of proportional representation, it has often lead to small minorities gaining kingmaking powers, but I do believe that the objective of electoral districting should be to produce results that are likely to fairly represent the wishes of the electorate.

Re: An impossibility theorem for gerrymandering

#19

Post by mathfan2 » Thu, Oct 12, 2017, 4:35 PM UTC

bloaf wrote: post #10

dragontamer wrote: post #4

So the question is if "Minimizing Efficiency Gap" is what we should be aiming for. Its a solid proposal, but I guess its up to the courts to decide if "Efficiency Gap" is a good metric. I guess I'll be interested in hearing the arguments as they come up.

I'm not sure I like the name "Efficiency Gap" but the metric of "require the overall district results be within a certain range of the popular results" seems pretty straightforward to me. I've always thought they should just reverse the order of operations. Instead of having people draw the districts, then machines evaluate them, they should have machines draw a bunch of potential "low efficiency gap" districts, then…

The main takeaway from the article is that sometimes there is a trade-off between nice geometrical shapes and proportional district results.

If a machine gave you a crazy-shaped district map because that's the only way to get "low efficiency gap", would you agree to them?

Re: An impossibility theorem for gerrymandering

#20

Post by djrogers » Thu, Oct 12, 2017, 4:35 PM UTC

cousin_it wrote: post #9

dragontamer wrote: post #4

So the question is if "Minimizing Efficiency Gap" is what we should be aiming for. Its a solid proposal, but I guess its up to the courts to decide if "Efficiency Gap" is a good metric. I guess I'll be interested in hearing the arguments as they come up.

It seems to me that a system with zero efficiency gap would be equivalent to one big election with proportional representation. If that's what people really want, why talk about voting districts at all?

You're either thinking about this too broadly, or as a system filled with static entities. Within voting districts, politics is local - individuals can sway voters, voters can decide to show up/skip voting, etc.

Also, the concept of a 'blue/red' district can be very blurry - there are many examples of 'blue' districts (districts with democrat congress reps, and a history of voting blue) that voted red in the last presidential election, and vice-versa for previous elections.

Historically, Americans prefer to vote for people, not parties.